Question

A solution is prepared by dissolving 4g of NaOH in distilled water to give

200ml of solution.Molarity of solution is:

(a) 0.5M (b) 0.1M (c) 0.05M (d) 0.2M​

Answer 1

Answer:

0.2M

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Answer 2

Given :-

• A solution is prepared by dissolving 4g of NaOH in distilled water to give 200ml of solution.

To Find :-

• Molarity of solution.

Solution :-

We know :-

$\bf \dag \underline{\boxed{\bf Molarity(M) = \dfrac{No \ of \ moles \ of \ solute}{Volume \ of \ solution \ in \ litres}}}$

First let's find no of moles in 4g of NaOH :-

$\longrightarrow \bf No \ of \ moles = \dfrac{Given \ mass }{Molar \ mass }$

• Atomic mass of Na = 23g
• Atomic mass of O = 16g
• Atomic mass of H = 1g

$\longrightarrow \sf No \ of \ moles = \dfrac{4}{23+16+1} \\\\\longrightarrow No \ of \ moles = \dfrac{4}{40} \\\\\longrightarrow No \ of \ moles = 0.1$

Molarity :-

$\longrightarrow \sf \dfrac{0.1}{200 \times \dfrac{1}{1000}} \\\\\\\longrightarrow 0.1 \times \dfrac{1000}{200} \\\\\longrightarrow \dfrac{1}{2} \\\\\longrightarrow \bf 0.5 \ M$

Molarity of solution = 0.5 M